before 900; (v.) Middle Englishsetten,Old Englishsettan; cognate with Old Norsesetja,Germansetzen,Gothicsatjan, all < Germanic*satjan, causative of *setjan to sit1; (noun) (in senses denoting the action of setting or the state of being set) Middle Englishset, set(t)e, derivative of the v. and its past participle; (in senses denoting a group) Middle Englishsette < Old French < Latinsectasect (in later use influenced by the v. and Middle Low Germangesette set, suite)

The verbs set and sit1 are similar in form and meaning but different in grammatical use. Set is chiefly transitive and takes an object: Set the dish on the shelf. Its past tense and past participle are also set: Yesterday he set three posts for the fence. The judge has set the date for the trial.Set also has some standard intransitive uses, as “to pass below the horizon” (The sun sets late in the northern latitudes during the summer) and “to become firm, solid, etc.” (This glue sets quickly). The use of set for sit, “to be seated,” is nonstandard: Pull up a chair and set by me.Sit is chiefly intransitive and does not take an object: Let's sit here in the shade. Its past tense and past participle are sat: They sat at the table for nearly two hours. Have they sat down yet? Transitive uses of sit include “to cause to sit” (Pull up a chair and sit yourself down) and “to provide seating for” (The waiter sat us near the window).

Intransitive sense from c.1200, "be seated." Used in many disparate senses by Middle English; sense of "make or cause to do, act, or be; start" and that of "mount a gemstone" attested by mid-13c. Confused with sit since early 14c. Of the sun, moon, etc., "to go down," recorded from c.1300, perhaps from similar use of the cognates in Scandinavian languages. To set (something) on "incite to attack" (c.1300) originally was in reference to hounds and game.

"collection of things," mid-15c., from Old French sette "sequence," variant of secte "religious community," from Medieval Latin secta "retinue," from Latin secta "a following" (see sect). "[I]n subsequent developments of meaning influenced by SET v.1 and apprehended as equivalent to 'number set together'" [OED]. The noun set was in Middle English, but only in the sense of "religious sect" (late 14c.), which likely is the direct source of some modern meanings, e.g. "group of persons with shared status, habits, etc." (1680s).

Meaning "complete collection of pieces" is from 1680s. Meaning "group of pieces musicians perform at a club during 45 minutes" (more or less) is from c.1925, though it is found in a similar sense in 1580s. Set piece is from 1846 as "grouping of people in a work of visual art;" from 1932 in reference to literary works.

"act of setting; condition of being set" (of a heavenly body), mid-14c., from set (v.) or its identical past participle. Many disparate senses collect under this word because of the far-flung meanings assigned to the verb:

"Something that has been set" (1510s), hence the use in tennis (1570s) and the theatrical meaning "scenery for an individual scene in a play, etc.," recorded from 1859. Other meanings OED groups under "miscellaneous technical senses" include "piece of electrical apparatus" (1891, first in telegraphy); "burrow of a badger" (1898). Old English had set "seat," in plural "camp; stable," but OED finds it "doubtful whether this survived beyond OE." Cf. set (n.1).

Set (n.1) and set (n.2) are not always distinguished in dictionaries; OED has them as two entries, Century Dictionary as one. The difference of opinion seems to be whether the set meaning "group, grouping" (here (n.2)) is a borrowing of the unrelated French word that sounds like the native English one, or a borrowing of the sense only, which was absorbed into the English word.

(sět) A collection of distinct elements that have something in common. In mathematics, sets are commonly represented by enclosing the members of a set in curly braces, as {1, 2, 3, 4, 5}, the set of all positive integers from 1 to 5.